To gain information about the macromolecules that are essential constituents of living matter, to see how they are arranged in the structures they form and to see how this arrangement is altered by infections and degenerative diseases. To study certain of these macromolecules, such as viruses and other proteins, in purified form after isolation from the living material. To improve the resolution of the electron microscope and to interpret the way in which images are formed near its limit of resolution.